In recent years, semiconductor light-emitting elements such as light-emitting diodes (hereinafter, LEDs) have been expected to become a new light source for lamps, due to their high efficiency and long useful life in comparison to incandescent and halogen light bulbs. The light output of such LED chips decreases as temperature increases. Accordingly, constraining temperature increases is an important concern in a lamp using the LED chips.
Conventional lamps have been proposed in which temperature increases are constrained for the LED chips (see Patent Literature 1 and 2).
The lamps described in Patent Literature 1 and 2 each include a substrate, a light-emitting module made up of a plurality of LED chips mounted on the substrate, a mount on which the light-emitting module is mounted, and a case holding the mount therein such that a part of the lamp remains exposed. The mount and the case are formed as a common whole. In these lamps, heat is produced by the LED chips and transferred through the mount and then effectively transferred to the case, thus constraining temperature increases of the LED chips.
Generally, these lamps use a light-emitting module in which the LED chips are affixed to the substrate by an adhesive made of silicone resin. As such, the heat produced by the LED chips is transferred to the substrate via the adhesive made of silicone resin.